This data block contains mass of each atomic species. It has the following format:
%BLOCK SPECIES_MASS [units] CCC1/I1 R1 CCC2/I2 R2 . . . %ENDBLOCK SPECIES_MASS
The first entry on a line is the symbol or atomic number of the species. This must correspond with the species symbol or atomic number of the species in the POSITIONS_FRAC or POSITIONS_ABS block. The second entry on each line is the mass of that species.
Not all of the species present in the system have to appear in the SPECIES_MASS block. Any that are not present will be assigned the default mass for that species. However, if the symbol specified for a species is not a standard symbol in the periodic table, the mass of the species must be specified.
[units] specifies the units in which the masses are defined. If no units are given, the default of atomic mass units is used.
%BLOCK SPECIES_MASS O 15.9989995956 Al 26.9820003510 Ti 47.9000015259 Cs 132.9049987793 %ENDBLOCK SPECIES_MASS
CASTEP keyword glossary
CASTEP cell keywords and data blocks